Vulnerability Details CVE-2025-69534
Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.HTMLParser to raise an unhandled AssertionError during Markdown parsing. Because Python-Markdown does not catch this exception, any application that processes attacker-controlled Markdown may crash. This enables remote, unauthenticated Denial of Service in web applications, documentation systems, CI/CD pipelines, and any service that renders untrusted Markdown. The issue was acknowledged by the vendor and fixed in version 3.8.1. This issue causes a remote Denial of Service in any application parsing untrusted Markdown, and can lead to Information Disclosure through uncaught exceptions.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 47.9%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2025-69534
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cpe:2.3:a:python-markdown:markdown:3.8